a lot for causes might be the reason for this reaction. I would suggest you to visit a doctor. But still, some of the cause to this might be: a brain-disfunction which bombed your muscles with motion signals. another explanation to this might be low temperature of your body which is hypothermia.

You probably have low blood sugar and/or blood pressure. Before getting out of bed, try doing some simple stretches while still laying down. This should get your blood moving before you hop out of bed in the morning.